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btrfs: Don't pass NULL ptr to func that may deref it. 

Hi,

In fs/btrfs/inode.c::fixup_tree_root_location() we have this code:

...
 		if (!path) {
 			err = -ENOMEM;
 			goto out;
 		}
...
 	out:
 		btrfs_free_path(path);
 		return err;

btrfs_free_path() passes its argument on to other functions and some of
them end up dereferencing the pointer.
In the code above that pointer is clearly NULL, so btrfs_free_path() will
eventually cause a NULL dereference.

There are many ways to cut this cake (fix the bug). The one I chose was to
make btrfs_free_path() deal gracefully with NULL pointers. If you
disagree, feel free to come up with an alternative patch.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Jesper Juhl 2010-12-25 21:22:30 +00:00 committed by Chris Mason
parent 20b450773d
commit ff175d57f0
1 changed files with 2 additions and 0 deletions
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2
fs/btrfs/ctree.c
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@ -105,6 +105,8 @@ noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
/* this also releases the path */ /* this also releases the path */
void btrfs_free_path(struct btrfs_path *p) void btrfs_free_path(struct btrfs_path *p)
{ {
if (!p)
return;
btrfs_release_path(NULL, p); btrfs_release_path(NULL, p);
kmem_cache_free(btrfs_path_cachep, p); kmem_cache_free(btrfs_path_cachep, p);
} }